Dynamic seal for use in a dental handpiece

ABSTRACT

A dynamic seal for use in a dental handpiece is disclosed. The dynamic seal includes a seal carrier including a first portion having a first feature for receiving a first compliant member and a second portion having a second feature for receiving a second compliant member, and a flange disposed between the first feature and the second feature.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation of U.S. Non-Provisionalapplication Ser. No. 15/625,392, filed Jun. 16, 2017, which is acontinuation of U.S. Non-Provisional application Ser. No. 14/716,075,filed May 19, 2015, now U.S. Pat. No. 9,707,050, which claims priorityand benefit of U.S. Provisional Patent Application No. 62/000,145,titled “Dental Medical Handpiece Having a Rotatable Inner Chamber,”filed May 19, 2014, the entirety of which is incorporated by reference.

FIELD OF THE INVENTION

The present invention is generally dental medical handpieces, dentalmedical systems including dental medical handpieces, dynamic seals foruse in dental medical handpieces, and processes of using dental medicalhandpieces. More particularly, the present invention is related to suchsystems, handpieces, dynamic seals for use in handpieces, and processesrelying upon ultrasonics.

BACKGROUND OF THE INVENTION

An ultrasonic dental tool typically includes a handpiece connected to acable that has lavage and connects electrical power, ground, andfeedback circuits. The cable may include a flexible tube to provide thelavage (for example, water chlorohexidine, and/or mouth wash). The cableconnects a scaling unit to the handpiece circuits.

During a typical ultrasonic cleaning procedure, a dentist or hygienistwill need to change the direction of an insert tip relative to the layof the cable in the dental tool in order to properly adapt to the toothsurface being cleaned. Because the insert to handpiece seal is a staticseal, it is not easily rotated because of frictional forces (from havinga tight fit). Typically, the insert must be removed from a patient'smouth and both hands of the dentist or the hygienist must be used torotate the tip (for example, moving from mandibular anterior tomaxillary premolar). Such action interrupts workflow and, thus,productivity. Without changing the orientation of the tip, the dentistor the hygienist would have to counter the cable's torsional load on thehandpiece in order to maintain proper tip angulation, which results in ahigher pinch grip force. Tighter pinch grips can be a source of fatigue,reduction in tactile sensitivity, and/or the ability to assure patientcomfort.

A dental medical handpiece, dental medical system including a dentalmedical handpiece, and a process of using a dental medical handpiecethat show one or more improvements in comparison to the prior art wouldbe desirable in the art.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, a dynamic seal for use in a dental handpiece includesa seal carrier including a first portion having a first feature forreceiving a first compliant member and a second portion having a secondfeature for receiving a second compliant member, and a flange disposedbetween the first feature and the second feature.

In another embodiment, a dynamic seal for use in a dental handpieceincludes a seal carrier including a first portion having a pair of firstfeatures for each receiving a first compliant member, and a secondportion having a pair of second features for each receiving a secondcompliant member, and a flange disposed between the first feature andthe second feature.

In another embodiment, an assembly includes a barrel of a dentalhandpiece, and a seal carrier connected to the barrel of the dentalhandpiece, the seal carrier including a first portion having a firstfeature for receiving a first compliant member and a second portionhaving a second feature for receiving a second compliant member, and aflange disposed between the first feature and the second feature.

Other features and advantages of the present invention will be apparentfrom the following more detailed description, taken in conjunction withthe accompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a dental handpiece in assembled form,according to an embodiment of the disclosure.

FIG. 2 shows a section view of a dental handpiece in assembled form,according to an embodiment of the disclosure.

FIG. 3 is a perspective view of a dental handpiece in disassembled form,according to an embodiment of the disclosure.

FIG. 4 is a perspective view of a coil unit for an embodiment of adental handpiece in disassembled form, according to the disclosure.

FIG. 5 is a side view of a portion of an embodiment of a dentalhandpiece having a canted coil spring securing a coil unit and an innerbarrel, according to the disclosure.

FIG. 6 is a perspective view of a portion of an embodiment of a dentalhandpiece having a body of increasing width to secure a coil unit and aninner barrel, according to the disclosure.

FIG. 7 is a perspective view of a portion of an embodiment of a dentalhandpiece having an incomplete annular structure securing a coil unitand an inner barrel, according to the disclosure.

FIG. 8 is a perspective view of an incomplete annular structure forsecuring a coil unit and an inner barrel, according to the disclosure.

FIG. 9 is a side view of an embodiment of a dental handpiece having aswivel drag adjustment screw, according to the disclosure.

FIG. 10 is a side view of an embodiment of a dental handpiece having adampener, according to the disclosure.

FIG. 11 is an enlarged view of the seal carrier.

FIG. 12 is a cross-sectional view of the inner sheath.

Wherever possible, the same reference numbers will be used throughoutthe drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION

Provided is a dental handpiece. Embodiments of the present disclosure,for example, in comparison to concepts failing to include one or more ofthe features disclosed herein, permit exposure to an increased number ofsterilization cycles, permit exposure to an increased range oftemperature cycles, allow use of autoclaving techniques not previouslypracticable, reduce or eliminate short-circuits, permit more dentistsand hygienists to be more productive, permit more dentists andhygienists to avoid fatigue and injury, generate other suitableadvantages that will be apparent from the present disclosure, or acombination thereof.

FIG. 1 shows a dental handpiece 100 capable of being used for supra andsub-gingival treatment, periodontal debridement, endodontic procedures,or other oral procedures. Referring to FIGS. 2-3, the dental handpiece100 includes an inner sheath, or barrel, 101 for rotatably retaining anultrasonic insert 103 (for example, allowing 360 degree rotation of theultrasonic insert 103). The inner barrel 101 is configured forcontacting the ultrasonic insert 103 with a cooling fluid 105 in theinner barrel 101. The dental handpiece 100 further includes a coil unit107 arranged and disposed to apply an alternating magnetic field 109 tothe ultrasonic insert 103 when positioned in the inner barrel 101, andan outer sheath 111 extending around at least a portion of the coil unit107. The dental handpiece 100 includes flow regions 113 permittingsteam, chemicals, and heat to flow into the inner barrel 101 and out ofthe inner barrel 101 during a sterilization technique.

The material for the elements of the dental handpiece 100 includes anysuitable material capable of withstanding temperature and pressure ofautoclaving. Such conditions are those that apply to using steamautoclaves, chemical vapor autoclaving, rapid dry heating, transfersterilization, dry heating, and/or ultrasonic cleaning, for example, atan operating temperature of 132° C. to 190° C. for 10 to 30 minuteswrapped, followed by 3 to 6 minutes unwrapped, in the presence ofchemicals such as formaldehyde and/or alcohol, and/or undercooling/drying conditions for 10-20 minutes. Suitable materials include,but are not limited to, polyetherimide, glass-fiber reinforcedmaterials, amorphous polyamide resin, and/or liquid crystal polymermaterial.

The outer sheath 111 protects users of the dental handpiece 100 (suchas, a dentist or hygienist) as well as those receiving treatment (suchas patients), for example, by preventing exposure to electrical contactsand coils, reducing or eliminating biological materials that can lead toinfection, and by including surfaces and profiles that allowdisinfectant wiping. Additionally, the outer sheath 111 permitsergonomic use of the dental handpiece 100. In general, the outer sheathis tubular and/or cylindrical, with an open interior. The outer sheath111 includes a larger open end 104 distal from a rotatable nozzle 115and a smaller open end 102 proximal to the rotatable nozzle 115. In oneembodiment, the larger open end 104 is capable of connection/separationfrom an external cable assembly 130 using securing mechanism 121, suchas, tabs and grooves within the outer sheath 111. Other suitablesecuring mechanisms 121 capable of being utilized within the dentalhandpiece 100 include, but are not limited to, seals (for example, oneor more dynamic seals 201), swivel bearing 126, clips, snap rings orretainers 125, retention coupler 124, and other features that permitdisassembly of the dental handpiece 100, features that facilitateremoval of debris within the dental handpiece 100, or a combinationthereof.

In one embodiment shown in FIG. 11, the dynamic seal 201 may include adynamic seal assembly 128 made of one or more compliant members, e.g.,an o-ring or a lip seal, arranged on a seal carrier 122. Seal carriermay be, e.g., a machined or molded component, or the like. Seal carrier122 may be manufactured to have a low friction high integrity surfacefree of defects, such that the seals 121 can rotate over the sealcarrier 122 with little to no friction and resultant wear. Seal carrier122 can be made of any suitable compliant material, e.g., Teflon®, sothat small degrees of misalignment or side loading can be absorbed andnot transferred in the seals due to uneven loading and potential loss ofcompression that may result in leakage. FIG. 12 shows a cross-sectionalview of the inner barrel 101. Inner barrel 101 may include receivinggrooves 131 for receiving seals 121, e.g., o-rings. Grooves 131 allowthe seal assembly 128 to fit precisely in an axial position with the end129 of inner barrel 101. Grooves 131 create a static seal, i.e.,non-rotational seal, between inner barrel 101 and coil unit 107 whilemaintaining the integrity of the seal 121 to prevent fluid passage. Aflange 132 may be provided on seal carrier 122 between static sealo-rings 121 a and dynamic seal o-rings 121 b, to provide a mechanicalstop to aid in alignment of seal carrier 122 in inner barrel 101.

In an embodiment including one of the dynamic seals 201 positionedproximal to the smaller open end 102, the dynamic seal 201 has adiameter that is ⅓ or less in length in comparison to the diameter ofthe outer sheath 111, thereby reducing friction between the dynamic seal201 and rotating surface of the dental handpiece 100, allowing for lessdrag during operation of the dental handpiece 100, allowing for smootheroperation of the dental handpiece 100, and/or allowing for operationwith torque of less than 1 inch-ounces (in-oz), or ½ in-oz, or 0.01in-oz, with torque being defined by the following equation:

Torque=μR_(S)R_(L)   (Equation 1)

According to the above equation, μ refers to the coefficient of frictionfor the dynamic seal 201, R_(S) refers to the radius of the seal carrier122, and R_(L) refers to axial loading. Referring to FIG. 10, in oneembodiment, the dental handpiece 100 includes a dampener 1001 extendingaround the coil unit 107 for balancing/equalizing pressure on thedynamic seal 201.

In one embodiment, the outer sheath 111 has limited or no crevices thatpermit bacteria or other biological materials to grow. For example, inone embodiment, the dental handpiece 100 is manufactured such thatcrevices exist only in flow regions 113, such as, in the larger open end104 of the dental handpiece 100 distal from the rotatable nozzle 115. Ina further embodiment, the flow regions 113 are formed by ribs or by aloose abutting fit between elements of the dental handpiece 100. Theflow regions 113 have any suitable dimensions. In one embodiment, theflow regions 113 are between 0.01 mm and 0.5 mm, between 0.02 mm and0.35 mm, at about 0.25 mm, or any suitable combination, sub-combination,range, or sub-range therein. In a further embodiment, the flow regions113 include at least two separate paths from outside of the dentalhandpiece 100 to the interior of the dental handpiece 100.

In embodiments including materials having different coefficients ofthermal expansion, crevices defining the flow regions 113 providesterilization passageways or openings, allowing fluid and heat into theinterior of dental handpiece 100 in order to sterilize the innerworkings of the handpiece. In one embodiment, the outer sheath 111 has afirst coefficient of thermal expansion and the coil unit 107 has asecond coefficient of thermal expansion, the first coefficient ofthermal expansion differing from the second coefficient of thermalexpansion (CTE). Some examples of CTEs are as follows:

For coil form material: Glass fibre reinforced engineering thermoplasticmaterial based on a combination of semicrystallinepPolyamide withpartially aromatic copolyamide.

23.0-55.0° C.

Coefficient of Thermal Expansion (Parallel) 9.00E-05/°K

Coefficient of Thermal Expansion (Normal) 1.50E-05/°K

Coil: Copper

20.0-100° C. 16.4 μm/°K

In a further embodiment, the difference between the coefficients ofthermal expansion is above a “fracture value,” the “fracture value”being a point where fixed/adhesive coupling would have damaged one orboth of the outer sheath 111 and the coil unit 107 during the flow offluid and/or heat during the sterilization technique, for example, bycracking or fracturing the outer sheath 111. In this embodiment, theouter sheath 111 and the coil unit 107 are not damaged during the flowof the fluid and/or the heat during the sterilization technique, despitesuch a difference between the coefficients thermal expansion being abovethe fracture value.

The outer sheath 111 extends around coil unit 107, and the coil unit 107extends around the inner barrel 101. The inner barrel 101 forms a sealwith the coil unit 107 abutting one or more of the securing mechanisms121, such as, o-rings, or dynamic seals. In one embodiment, proximal tothe larger open end 104 of the outer sheath 111, the securing mechanism121 is a dynamic seal that creates a lower amount of drag on ultrasonicinsert 103 in comparison to drag on other elements from other sealswithin the dental handpiece 100. The dynamic seal permits the coolingfluid 105 to flow from being proximal to the larger open end 104 tobeing proximal to the smaller open end 102, while within the ultrasonicinsert 103, prior to cooling and exiting a scaler 119 (such as, a 30 kHzmagnetorestrictive scaler) positioned within the rotatable nozzle 115.

The rotatable nozzle 115 extends from the inner barrel 101, for example,through a grip region 117. The grip region 117 includes a material, suchas, an elastomeric material, for handling by the user. In oneembodiment, the scaler 119 and/or the ultrasonic insert 103 is/areselectively rotatable, capable of being locked in a fixed position,configured for operation at different torque levels (for example, at alower torque level and a higher torque level), or a combination thereofin response to application of a force (such as a torsional load) to thegrip region 117. Alternatively, other suitable dental devices areincluded instead of the scaler 119. Referring to FIG. 9, in oneembodiment, the torque is adjusted from the lower torque level to thehigher torque level by rotating a swivel drag adjustment screw 901positioned to extend from within the dental handpiece 100 to outside ofthe dental handpiece 100 where it is adjustable by the dentist or thehygienist. Other suitable mechanisms for torque adjustment include knobs(for example, extending around the outer sheath 111), buttons, clutchassemblies, preloaded barrels, and/or combinations of large and fineadjustment knobs.

The coil unit 107 is within the outer sheath 111 of the dental handpiece100, for example, being movably secured therein. For example, coil unit107 extends around inner barrel 101 for rotatably retaining ultrasonicinsert 103 (for example, allowing 360 degree rotation of the ultrasonicinsert 103), as previously discussed, and further, as shown in FIGS. 2,3, 11 and 12, coil 107 is independently rotatable relative to innerbarrel 101 as a result of corresponding portions of the inner surface ofthe coil 107 being in contact with dynamic seal o-rings 12 b of dynamicseal assembly 128 and swivel bearing 126, and more specifically, as aresult of the seals 121 (i.e., both static and dynamic seal o-rings 121a, 121 b) being rotatable over the seal carrier 122 with little to nofriction and resultant wear, as previously discussed, the dentalhandpiece of the present invention is not susceptible to rotational dragor binding suffered by conventional dental handpieces as a result of abent or damaged ultrasonic insert. As shown in FIG. 4, in oneembodiment, the coil unit 107 is capable of being secured within theouter sheath 111 by having alignment members and/or one or moreretaining elements, e.g., coupling pins 401; one or more alignmentregions, e.g., as channels 403 corresponding with the coupling pins 401.Coupling pins 401 may provide electrical contacts for the cable assembly130. Interfacial seals 422 may be provided to provide a fluid sealbetween the outer sheath 111 and the cable assembly. Interfacial seals422 have an annular opening for receiving one end of a coupling pin 401.Coil unit may also include one or more mating sockets in the cableassembly 130, flanges, molded receptacles, other suitable alignmentdevices, or a combination thereof.

The coil unit 107 generates the magnetic field 109 that oscillates theultrasonic insert 103 and, thus, the scaler 119. In one embodiment, thecoil unit 107 includes a coated coil wire 123 to extend around theultrasonic insert 103 (or the region where the ultrasonic insert 103 isto be positioned). The coating reduces or eliminates shorting of thecoil unit 107 during the generation of the magnetic field 109.

The coil unit 107 includes other suitable elements, such as abucking/feedback coil 405 extending from a drive coil 407 in electricalcommunication with electrical contacts 409, which are capable of beingthe coupling pins 401. The bucking/feedback coil 405 and the drive coil407 conduct electricity from an alternating current source thatgenerates the magnetic field 109. The bucking/feedback coil 405 and/orthe drive coil 407 are secured to a coil form 411 which serves as a basestructure for the coil unit 107, for example, between flanges 413. Wireswithin the bucking/feedback coil 405 and/or the drive coil 407 areconnected to terminals (not shown), provide power, register feedback,and act as a common ground.

A feedback portion of the bucking/feedback coil 405 includes a firstwire 415 having a gauge that is smaller than a second wire 417 in thedrive coil 407 to register voltage developed by movement of, forexample, the ultrasonic insert 103. In one embodiment, the first wire415 is wound in five layers beginning on a polytetrafluoroethylene tapewhich is directly against the coil form 411 between the flanges 413 andis connected to a ground terminal and feedback terminal (not shown). Inone embodiment, the first wire 415 is polytetrafluoroethylene-coatedcopper wire with 0.0007 to 0.0011 inch thick insulation on 38 gaugewire.

A bucking portion of the bucking/feedback coil 405 includes a third wire419, for example, wound in one layer, over the feedback portion of thebucking/feedback coil 405. In one embodiment, the third wire 419 ispolytetrafluoroethylene-coated copper wire with 0.0020 to 0.0029 inchthick insulation on 22 gauge wire. The bucking portion reduces oreliminates transformer coupling between the drive coil 407 and thefeedback portion of the bucking/feedback coil 405. The bucking portionof the bucking/feedback coil 405 and the drive coil 407 are connectedbetween terminals and in one continuous wire.

The drive coil 407 is attached to the terminal using a right-hand turn,for example, being wound from the flange 413 to the flange 413 and back.The second wire 417 from the drive coil 407 then traverses space betweenthe flanges 413 using a left-hand turn, being wound between the flanges413 to connect to the bucking portion of the bucking/feedback coil 405.In one embodiment, the second wire 417 is the same, or substantially thesame, in size and/or design as the third wire 419.

The bucking portion of the bucking/feedback coil 405 and the drive coil407 are wired in series and in opposite directions, resulting in beingelectromagnetically 180° out of phase. The bucking portion of thebucking/feedback coil 405 is electrically insulated from the feedbackportion of the bucking/feedback coil 405.

In one embodiment, interposed between all winding layers of the feedbackportion and the bucking portion of the bucking/feedback coil 405 is alayer of polytetrafluoroethylene tape (not shown), for example, at about0.002 inches in thickness. The polytetrafluoroethylene tape is capableof being positioned on polyester and/or polyamide-imide insulation oncopper wires. In one embodiment, the polytetrafluoroethylene tape isalso used between the layers of the drive coil 407.

The polytetrafluoroethylene tape and/or thepolytetrafluoroethylene-coating increases interlayer insulation, whichprolongs the life and the number of autoclaving cycles the dentalhandpiece 100 is capable of experiencing prior to any shorting. Ingeneral, the polytetrafluoroethylene is conformable, chemically inert,nonporous, withstands a continuous cycle of temperature from 0° C. to atleast 205° C., has high and low temperature stability, has excellentelectrical properties, and has good adhesion to copper conductors.Alternatively, in other embodiments, one or more of the elements of thecoil unit 107 are devoid of the polytetrafluroethylene tape.

In one embodiment, the dental handpiece 100 is devoid of potting. Beingdevoid of potting further permits steam, chemicals, and/or heat to passinto and out of the interior of the dental handpiece 100, allows for theheating and cooling expansion and contraction of parts of differentcoefficients of thermal expansion without the developing electricalshort-circuits, and allows sterilization of the dental handpiece 100.

According to one embodiment, the dental handpiece 100 is assembled by aninitial assembly of the inner barrel 101 with the securing mechanisms121, for example, bearings, in the larger open end 104 and the smallopen end 102, and an initial assembly of the coil unit 107. The innerbarrel 101 and the coil unit 107 are then secured together, for example,by being locked/snapped together.

As shown in FIG. 5, in one embodiment, the inner barrel 101 and the coilunit 107 are removably secured by a canted coil spring 501 positionedbetween the inner barrel 101 and the coil unit 107. In a furtherembodiment, a non-toxic compatible lubricant, such as food-gradesilicone or teflon, is included in contact with the canted coil spring501.

As shown in FIG. 6, according to an embodiment, one suitable techniquefor securing the inner barrel 101 and the coil unit 107 or for securingother elements of the dental handpiece 100 includes positioning bodies601 having an increasing width (for example, based upon a first width602 being smaller than a second width 604 along an insertion direction606) into open regions 603 in a direction 608 perpendicular to theinsertion direction 606 prior to insertion of the coil unit 107.

Referring to FIGS. 7 and 8, according to one embodiment, a technique forsecuring the inner barrel 101 and the coil unit 107 or for securingother elements of the dental handpiece 100 includes an incompleteannular structure 701 that has protruding portions 703 and is capable ofcompression during insertion of the coil unit 107, for example, byhaving a disconnected opening 705.

After securing the inner barrel 101 and the coil unit 107, the assemblyof the inner barrel 101 and the coil unit 107 is inserted into the outersheath 111, for example, such that the flanges 413 of the coil form 411engage the interior wall of the outer sheath 111, for example, byfrictionally locking. The rotatable nozzle 115 is then secured to theremaining portions of the assembly to produce the dental handpiece 100.Upon being assembled, the dental handpiece 100 is then capable ofcoupling and operation with a system capable of operating the dentalhandpiece 100. An instrument, such as, the scaler 119 is then capable ofbeing inserted during operation of the dental handpiece 100 by thedentist or hygienists, as described above.

While the invention has been described with reference to one or moreembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. In addition, all numerical values identified in the detaileddescription shall be interpreted as though the precise and approximatevalues are both expressly identified.

What is claimed is:
 1. A dynamic seal for use in a dental handpiece,comprising: a seal carrier including a first portion having a firstfeature for receiving a first compliant member and a second portionhaving a second feature for receiving a second compliant member; and aflange disposed between the first feature and the second feature.
 2. Thedynamic seal of claim 1, wherein the seal carrier has a low frictionhigh integrity surface free of defects.
 3. The dynamic seal of claim 1,wherein the first portion and the second portion are axially aligned,the flange extending radially outwardly from the axis.
 4. The dynamicseal of claim 1, wherein the seal carrier is composed of a compliantmaterial.
 5. The dynamic seal of claim 4, wherein the seal carrier iscomposed of polytetrafluoroethylene.
 6. The dynamic seal of claim 1,wherein the first portion is adapted to connect to the dental handpiece.7. A dynamic seal for use in a dental handpiece, comprising: a sealcarrier including a first portion having a pair of first features foreach receiving a first compliant member, and a second portion having apair of second features for each receiving a second compliant member;and a flange disposed between the first feature and the second feature.8. The dynamic seal of claim 7, wherein the first portion and the secondportion are axially aligned, the flange extending radially outwardlyfrom the axis.
 9. The dynamic seal of claim 7, wherein the seal carrierhas a low friction high integrity surface free of defects.
 10. Thedynamic seal of claim 7, wherein the seal carrier is composed of acompliant material.
 11. The dynamic seal of claim 10, wherein the sealcarrier is composed of polytetrafluoroethylene.
 12. The dynamic seal ofclaim 7, wherein the first portion is adapted to connect to the dentalhandpiece.
 13. An assembly comprising: a barrel of a dental handpiece;and a seal carrier connected to the barrel of the dental handpiece, theseal carrier including a first portion having a first feature forreceiving a first compliant member and a second portion having a secondfeature for receiving a second compliant member, and a flange disposedbetween the first feature and the second feature.
 14. The assembly ofclaim 13, wherein the first portion and the second portion of the sealcarrier are axially aligned, the flange extending radially outwardlyfrom the axis.
 15. The assembly of claim 13, wherein the seal carrierhas a low friction high integrity surface free of defects.
 16. Theassembly of claim 13, wherein the seal carrier is composed of acompliant material.
 17. The assembly of claim 16, wherein the sealcarrier is composed of polytetrafluoroethylene.
 18. The assembly ofclaim 13, wherein the first portion is connected to the barrel of thedental handpiece.
 19. The assembly of claim 18, wherein an end of thebarrel is adapted to receive the flange.
 20. The assembly of claim 13,wherein the second portion is adapted to connect to the dentalhandpiece.